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Will My Prescription Drug Show Up on My Toxicology Screening? What You Need to Know

Jul 15, 2022

Toxicology screening is an essential component of the application process for many businesses, schools, athletic organizations, and rehabilitation programs. However, sometimes other factors may deliver erroneous results, leading to adverse consequences for individuals. For instance, some prescription medications produce false positives. To ensure you obtain accurate outcomes from drug testing and screening, TOPLAB® discusses how different medicines may interfere with results.

What Is Included in a Toxicology Screen?

During a toxicology test, a laboratory technician examines a specimen sample for various drugs in the body. Most drug screenings involve taking a urine or saliva sample, but some people undergo blood work or sweat tests to obtain results.

Depending on the specific test, a toxicology screening could detect one drug or closer to 30. These assessments also identify various substances, including illegal drugs, alcohol, prescription medications, over-the-counter medicine, and even vitamins and supplements. Consequently, medications that share similarities with the drugs the employer is looking for may lead to a false positive.

What Prescription Medications Impact Drug Test Results?

The main reason for drug testing is to verify people do not consume substances that may alter their performance. However, prescription medicines are intended to help people manage a variety of health conditions. By creating false positives, these medications may incriminate people and prevent them from obtaining a job or participating in an event. Individuals should watch out for false positives with the following prescriptions:

Quinolone Antibiotics

Doctors often prescribe quinolone antibiotics for sinus infections, pneumonia, urinary tract infections, tuberculosis, and similar illnesses. These drugs frequently turn out false positives during urine drug screening procedures for opiates.


Histamine is a chemical that originates in the body’s immune system. When it overreacts, the person experiences allergic symptoms, such as coughing and watery eyes. Antihistamines treat allergies and some other conditions, including stomach issues and anxiety. Some antihistamines and related sleep aids can cause false positives during drug tests.


Analgesics, also known as non-steroidal anti-inflammatory drugs (NSAIDs), may cause false positives in tests looking for barbiturates, marijuana, or PCP. Some analgesics prescribed for arthritis also generate inaccurate outcomes during toxicology screenings.


People with mental health concerns taking antidepressants may receive a false positive on tests for LSD or amphetamines. These outcomes will vary based on the specific antidepressant.

Proton Pump Inhibitors

Physicians treating patients with gastroesophageal reflux disease (GERD), peptic ulcer disease (PUD), or other disorders causing heartburn often prescribe proton pump inhibitors. If a person uses this treatment daily, their urine screening for marijuana may come back positive.

Over-the-Counter Medications

Some generic medications used to treat cold and flu symptoms, such as decongestants and cough suppressants, lead to false positives for tests examining opiates, PCP, and methamphetamines. These medicines may contain some of the same ingredients as these more notorious substances.

Central Nervous System Stimulants

These medications help patients suffering from ADHD, depression, and narcolepsy. Central nervous system stimulants have been known to deliver false positives in tests for amphetamines and methamphetamines.

Seek Accurate Drug Testing Services from TOPLAB®

Since many medications can interfere with toxicology screenings, a trusted partner that delivers reliable results can be a true asset. As a full-service clinical reference laboratory, TOPLAB® uses the most updated technology to produce quick, accurate outcomes. In addition to serving consumers, we also offer employee drug screening services to assist businesses. Many other labs send samples to TOPLAB® since our facility has the resources to perform urine and oral fluid toxicology screenings. Contact us today to learn more about drug testing and screening for patients, physicians, and employers in New Jersey and nationwide.